Rookie Investor - STR looks appealing

[Vincent Samaha]

Hello. First post. I've been listening to the podcast/videos. I've recently begun realizing that my 401k will very likely be insufficient for retirement (I'm 37), so I'm searching for alternative investments. Instead of thinking of my later years as "retirement", it's better to call them the "passive income years", and real estate seems to fit perfectly within that idea. 

Since our family is regularly on the paying side of STRs through VRBO, it's something we're familiar with, and my wife and I have jokingly talked about buying a cabin in the Smoky Mountains or a beach house on Dauphin for personal use and rental income.

But I don't want to joke anymore. If we just play it safe and let someone else plan for our "passive income years", we won't be having passive income. 

So where should I start with STRs? Can I annualize the estimated income from a site like AirDNA and plug the numbers into a normal rental calculator to analyze the investment? What metrics should I prioritize?

Thanks for your help